Zinnias are long bloomers lasting from summer until first frost.
image by Linda DuBose: sxc.hu
An annual, zinnias bloom profusely, producing large, colorful flowers. They add color to late-summer and fall gardens with a long flowering period that starts in midsummer. Available in a range of colors, including pink, orange, yellow and white, there are also multicolored varieties. Miniature zinnias are suited to borders and containers, with large and giant varieties that reach as tall as 3 feet able to hold their own in garden beds. Zinnias grow from seed and are started outdoors after the last frost, although indoor sowing is recommended.
Fill starter flats with seed-starting soil mix. To start seeds indoors, plant them six to eight weeks before the last frost in your area.
Sow seeds approximately 6 inches apart on top of the soil, then cover them with approximately 1/4 inch of soil.
Water the seeds thoroughly from the bottom of the flat, or mist them with a spray bottle from the top. Set the flats in a warm place to germinate, approximately seven days.
Choose a sunny garden bed that is shaded in afternoon. Amend the soil by working in compost---zinnias prefer rich, well-drained soil but are tolerant of average soil.
Transplant your zinnias in the garden after all danger of frost has passed. Using a trowel, dig holes 6 to 8 inches apart in rows. Place each seedling in a hole and then fill it back in, gently pressing soil around the stem.
Keep soil moist at all times but not soaking wet. Water as needed and more often during the hot, dry months. Add an organic mulch around the zinnia plants to control weeds and preserve moisture in the soil.
Fertilize once a month during the growing season with a general-purpose fertilizer.
Pinch off spent blooms before seed heads form to encourage further flower production. Gently grasp the stem beneath the flower head between your thumb and forefinger and pinch the flower head off.